U.K. Prime Minister Gordon Brown apologized Wednesday after an open microphone caught him calling a voter a "bigoted woman."

The blunder was the first major mistake of the British election campaign for Brown leading up to the country's May 6 vote.

At a campaign stop in the northern town of Rochdale, Gillian Duffy, a 66-year-old grandmother who has been a lifelong supporter of Brown's Labour Party, questioned the prime minister about taxes, university fees, immigration and the country's deficit.

Duffy is a retired widow who had worked with handicapped children.

As he went to get into his waiting car, Brown said to Duffy: "Very nice to meet you."

However, after the exchange, Brown, who didn't realize the Sky News wireless microphone he was wearing was still on, told an aide: "That was a disaster, they should never have put me with that woman. Whose idea was that? It's just ridiculous."

Called to apologize

When asked what Duffy had said to upset him, Brown replied to his aide: "Everything. She's just a sort of bigoted woman."

The British Broadcasting Corp. later played the recording for Brown, who put his head in his hand.

Brown said he had called Duffy to apologize, and his campaign bus later pulled up outside her house for the prime minister to speak to her in person. He spent about 30 minutes at her home.

"I've apologized to her and I hope she'll accept my apology," Brown said.

Asked by reporters about the exchange, Duffy said she would likely abstain from voting next month.

"He's an educated person, why has he come out with words like that?" Duffy said. "He's calling an ordinary woman who's just come up and asked questions ... a bigot."

'Reveal the truth'

Brown's opponents pounced on his gaffe.

"The thing about general elections is that they reveal the truth about people," said George Osborne, a senior Conservative Party lawmaker, alluding to suggestions that Brown has a sharp temper

Labour Party members rushed to the prime minister's defence.

"This is something that he knows he shouldn't have said," said Treasury chief Alistair Darling.

An analyst said Brown's mistake may not prove fatal to his election hopes.

"People know that Brown is no angel, and though this won't do him any good, it's not certain how his will play out," said Ivor Gaber of London's City University.